Mina Seward is based upon the character of Wilhelmina "Mina" Harker (née Murray) as first depicted in Bram Stoker's 1897 novel, Dracula. The character has gone through many permutations, but is present in nearly all film adaptations of Stoker's work. The role has been played by several different actresses including Greta Schröder, Helen Chandler, Isabelle Adjani, Winona Ryder, Peta Wilson, Amy Yasbeck and Zoe Tapper.

In 1931, Mina and her father and friends attended the symphony at the theater, where she met the Transylvanian nobleman, Count Dracula. Mina was not nearly as impressed with the mysterious count as her friend Lucy was, and teased Lucy by mocking the count's thick Transylvanian accent.

That evening, Mina spent the night at Lucy Weston's place. It would be the last time she would ever see her friend alive. Dracula was not only a Transylvanian nobleman, but also a vampire, hungry for human blood. He fed from Lucy and killed her while Mina slept. A few nights later, Dracula entered Mina's room at the sanitarium and fed from her as well. He didn't take enough blood to kill her, but she awakened in a weakened state.

The following morning, Doctor Seward and John Harker examined her. Also in attendance was Doctor Seward's colleague, the occult scholar Professor Van Helsing. Wearing a scarf to conceal the bite wounds around her neck, Mina recounted a nightmare she had wherein she heard wolves howling and a thick mist filling the room. She also described a white face with piercing red eyes through the fog. Upon closer inspection, Professor Van Helsing discovered two small puncture wounds on the side of her neck. At this time, Dracula paid a visit to the Sewards and showed an interest in Mina's condition. It was then that Professor Van Helsing learned that Dracula was a vampire, though he was unable to take action against him directly.

Mina went out into the hospital gardens where she met Dracula. Enveloping her in his cape, Dracula bit her a second time. Moments later, a nurse discovered her and told the others that Mina was dead. They raced outside to attend her, but fortunately the nurse was mistaken and Mina was still alive.

The following evening, Mina had a chance encounter with Lucy Weston, who was now a vampire. Lucy visited her at Mina's bedroom window and was described as having a hungry look about her "like a wild animal". She then turned and fled back into the darkness. Mina recounted the story to Professor Van Helsing.

Mina began to realize what was happening to her. She told John that although she loved him, they could never be together again. She begged him not to touch her. John wanted to take Mina away from the sanitarium, but Seward and Van Helsing insisted that she must remain in the hospital until they can put an end to the threat of the vampire once and for all.

Van Helsing instructed Nurse Briggs to make sure that Mina wore a wreathe of wolfsbane while she slept. This tactic proved fruitless however as Dracula hypnotized Briggs and had her remove the wolfsbane. He then encountered Van Helsing a second time and warned him that his blood now flowed through Mina's veins and before the sunrise, she would be his forever.

Dracula took Mina from the terrace outside her room and brought her back to his crypt at Carfax Abbey. His lunatec servant Renfield accidentally led Professor Van Helsing and John Harker back to the crypt and they now knew where Dracula kept his coffin. As the sun was beginning to rise, he was forced to return to his coffin. While Professor Van Helsing drove a stake into the vampire's heart, John looked after Mina. With the death of Dracula, Mina was no longer under his thrall. John walked her up the stairs of the abbey into the sunlight.

Mina being the daughter of Doctor Seward is a detail that is unique to the Dracula film and stage production. In the original novel, she had no family connections to anyone other than Jonathan Harker. The Mina/Seward relationship is revisited in the 1995 farcical Dracula: Dead and Loving It.

Mina's Spanish counterpart in Drácula is named Eva and is played by Lupita Tovar.